My nuts for yours .....
I have four nos DC tan brake blocks which I think are from a set of 901's and have the 901 type of nut fitted .....
Am I right in thinking the 901's were '85 onwards ?
Anyway , I'm building an '83 bike with 890's , so would like the domed type of nut also found on DC blocks in exchange for mine ...... or I'll buy some if anyone has any ?